[hulitu]

This is because they are all monopolies.

My employer only allows Windows for PCs and iOS for phones.

If i buy i smartphone at a resonable price there is only Android. (no i will not pay 500 Euros for a thing that costs 50 Euros).

[pjmlp]

How many games written with the NDK in C/C++/OpenGL ES/Vulkan/OpenSL get ported from Android or ChromeOS into GNU/Linux?

Almost none, instead Windows gets kind of emulated via Proton, thus making irrelevant any business reasons to target GNU/Linux directly.